Barrier layer and surface preparation thereof

Abstract

In some examples, the disclosure describes an article and a method of making the same that includes a substrate defining an outer surface, a barrier layer on the outer surface of the substrate, the barrier layer defining a textured surface having a plurality of cells, each cell having a geometry and a depth, and an overlying layer formed on the textured surface of the barrier layer. The barrier layer may be configured to reduce migration of material from the substrate to the overlaying layer to reduce or prevent formation of cristobalite phase thermally grown oxide.

The invention claimed is: 
     
       1. An article comprising:
 a substrate defining an outer surface, the substrate including boron; 
 a barrier layer on the outer surface of the substrate, wherein the barrier layer includes silicon carbide, wherein the barrier layer defines a textured surface having a plurality of cells, each cell having a geometry in a major plane of the barrier layer and a depth; 
 a bond coat on the textured surface of the barrier layer; and 
 an environmental barrier coating (EBC) on a surface of the bond coat, the EBC having a porosity of less than about 20 volume percent, wherein the EBC defines a non-textured surface which defines an outer surface of the article, and 
 wherein the barrier layer is configured to reduce overall migration of the boron into the bond coat to reduce formation of crystalline phase thermally grown oxide between the bond coat and the EBC. 
 
     
     
       2. The article of  claim 1 , wherein the surface of the bond coat comprises a second textured surface, and wherein the EBC is formed on the second textured surface of the bond coat. 
     
     
       3. The article of  claim 1 , wherein the substrate comprises a ceramic or a ceramic matrix composite. 
     
     
       4. The article of  claim 1 , wherein the article comprises a component of a high temperature mechanical system, wherein the geometry of a respective cell of the plurality of cells is based on a predicted stress at the respective cell during operation of the high temperature mechanical system. 
     
     
       5. The article of  claim 1 , wherein the geometry comprises a width of a respective cell of the plurality of cells, wherein the width is within a range from about 5 microns to about 250 microns, and wherein the depth of each cell is within a range from about 1 micron to about 75 microns. 
     
     
       6. The article of  claim 1 , wherein the textured surface of the barrier layer comprises a surface roughness (Ra) within a range from about 3 microns to about 75 microns. 
     
     
       7. The article of  claim 1 , wherein the barrier layer defines a thickness within a range from about 5 microns to about 100 microns. 
     
     
       8. The article of  claim 1 , wherein the depth of a respective cell is different than the depth of at least one adjacent cell. 
     
     
       9. The article of  claim 1 , wherein a density of the barrier reduces the migration of the boron from the substrate into the bond coat. 
     
     
       10. The article of  claim 1 , wherein the barrier layer is a continuous layer over the outer surface of the substrate. 
     
     
       11. A gas turbine engine component, comprising:
 a ceramic composite matrix (CMC) substrate defining an outer surface, the substrate including boron; 
 a silicon carbide barrier layer on the outer surface of the substrate, wherein the barrier layer defines a textured surface having a plurality of cells, each cell having a geometry in a major plane of the barrier layer and a depth; 
 a bond coat formed on the textured surface of the barrier layer; and 
 an environmental barrier coating (EBC) formed on the bond coat, the EBC having a porosity of less than about 20 volume percent, and 
 wherein the barrier layer is configured to reduce migration of the boron from the CMC substrate into the bond coat to reduce formation of crystalline phase thermally grown oxide between the bond coat and the EBC. 
 
     
     
       12. The gas turbine engine component of  claim 11 , wherein the bond coat defines a second textured surface having a second plurality of cells, and wherein the EBC is formed on the second textured surface of the bond coat. 
     
     
       13. A method for forming an article, the method comprising:
 forming a barrier layer on an outer surface of a substrate; 
 texturing a surface of the barrier layer to form a textured surface by forming a plurality of cells in the barrier layer, each cell having a geometry in a plane of the barrier layer and a depth; 
 subsequently forming a bond coat on the textured surface of the barrier layer; and 
 forming an environmental barrier coating (EBC) on a surface of the bond coat, the EBC having a porosity of less than about 20 volume percent, wherein the EBC defines a non-textured surface which defines an outer surface of the article, and 
 wherein the barrier layer is configured to reduce overall migration of the boron into the bond coat to reduce formation of crystalline phase thermally grown oxide between the bond coat and the EBC. 
 
     
     
       14. The method of  claim 13 , wherein forming the bond coat further comprises texturing the surface of the bond coat to form a second textured surface, and wherein forming the EBC comprises forming the EBC on the second textured surface of the bond coat. 
     
     
       15. The method of  claim 13 , wherein the substrate comprises a ceramic or a ceramic matrix composite, and wherein forming the barrier layer comprises forming, by chemical vapor deposition, a silicon carbide barrier layer on the outer surface of the substrate. 
     
     
       16. The method of  claim 13 , wherein the article comprises a component of a high temperature mechanical system, wherein texturing the barrier layer comprises forming the plurality of cells based on a predicted stress at each respective cell of the plurality of cells during operation of the high temperature mechanical system. 
     
     
       17. The method of  claim 13 , wherein texturing the surface of the barrier layer comprises removing, by laser ablation or non-ablation laser surface modification, at least a portion of barrier layer to form the plurality of cells. 
     
     
       18. The method of  claim 13 , wherein forming the barrier layer comprises forming, by chemical vapor deposition, a silicon carbide barrier layer, and wherein the method further comprises thermal spraying a second silicon carbide barrier layer on the textured surface of the barrier layer. 
     
     
       19. The method of  claim 13 , wherein the barrier layer defines a thickness within a range from about 5 microns to about 100 microns. 
     
     
       20. The method of  claim 13 , wherein the depth of a respective cell is different than the depth of at least one adjacent cell.